Running into an issue in Qt5 on OS X where calling

QCoreApplication::processEvents()

with the `ExcludeUserInputEvents` flag is causing keystrokes to get dropped on the floor instead of deferred until the next time `processEvents()` is called without that flag. This is resulting in issues for us trying to update the ui during longer operations without accepting user input, as any typing the user was doing can end up riddled with typos.

Expected: Keystrokes pressed while the long timer operation is firing will get queued up and dispatched after the timer operation completes

Observed: Keystrokes are instead discarded, resulting in garbled text

Cause: Calling QCoreApplication::processEvents(QEventLoop::ExcludeUserInputEvents) after a long operation. As per the docs, the `KeyEvent`s should be deferred, not discarded.

This works as expected in Qt4 as well as on Windows Qt5

To reproduce: See attached example. Try typing in the QLineEdit and notice keystrokes are getting lost instead of deferred